The long term objectives are to improve understanding of functional organization or how the brain works as a system, focusing on the level of organized assemblies of neurons, and using lower vertebrae species as models. Specific aims are to compare physiological mechanisms of integration, filtering, encoding, reorganizing, and controlling response to sensory input, from sense organs to highest forebrain areas. Included is a search for event related potentials in nonmammals under stimulus regimes that cause mental events in humans (e.g. "There's one!"). Specific questions about the processing of sensory input from lateral line, somatosensory, acoustic and visual receptors in three brain regions: cerebrum, cerebellum, and brainstem are the special focus. Selected fish and reptiles will the main materials. These will be studied by the following physiological methods. Electrical signs of ongoing background brain activity and of responses will be recorded, rarely intracellularly, usually extracellularly from single unit spikes to multiunit spikes and compound, slow field potentials with single and multiple electrodes in linear arrays, comb-like and brush-like arrays. Analyses will include RMS amplitude, power, phase and coherence spectra, auto- and cross- correlations, band-passed displays, envelopes of AM of the band-passed data, spectra of envelopes, histograms, and average wave forms. Event related potentials will be sought in nonmammalian species using as nearly as possible the same paradigms as those applied to monkeys, cats and rats for omitted stimuli in a train, mismatch negativity, contingent negative variation and oddball stimuli, the last two requiring conditioning. Anatomical controls will localize electrode positions. The project will occupy the P.I., two postdocs, visiting investigators, one or two students, an engineer, technician and administrative assistant and is jointly supported by an NSF grant. Continued collaborations with former visiting scientists as well as new collaborations with local and distant colleagues are planned.